The best alternatives to Boomerang are Google Translate, Unbabel, and LingoJam. If these 3 options don't work for you, we've listed a few more alternatives below.
What do you think of Boomerang?
AssemblyAI— Speech-to-Text API with superhuman accuracy
Unbabel combines state of the art AI translation with a global community of editors to ensure that companies can talk to their customers in any language through email, chat and, FAQs at native quality, without hiring any extra agents.